Ivan has 15 yards of green felt and 12 yards of blue felt to make 3 quilts. If Ivan uses the same total number of yards for each quilt, how many yards does he use for each quilt?
You're just dividing the total yards of each felt evenly across the 3 quilts. 15/3 and 12/3 mean Ivan will use 5 yards of green felt and 4 yards of blue felt per quilt, for a total of 9 yards per quilt.